Liquid indicator



Sept. 20, 1932. PERKINS 1,878,801

LIQUID I NDICATOR '3 Filed June 11. 1929 jiweaazpr' 10 Per/Ziraa Patented Sept. 20, 193 52 LEE PERKINS, OF BELMONT, MASSACHUSETTS LIQUID INDICATOR Application filed June .1-1, 192! 9.' Serial No. 369,994.

This invention relates to apparatus for indicating the density of liquid within a liquid container or liquid containing system, and

I incidentally for showing the approximate 6 amount of liquid therein. While apparatus of the, character provided bv the present invention is generally applicable to such uses, it is particularly advantageous and intended for employment in conjunction with a cooling 10 system for mechanisms such as an internal combustion engine. v

For example, the ordinary water cooled automobile motor is connected with a radiator through which the cooling medium circulates,

a circulating pump ordinarily being provided to insure the positive circulation of this medium. In order to prevent freezing of the coolant when the vehicle is being driven under low temperature conditions, the water which is commonly used as the cooling medium may be mixed with a liquid having a lower freezing point such, for example, as alcohol, glycerine or the like. The freezing point of such a mixture depends upon the proportions of the water and the low freezing point liquid mixed therewith. Since the liquids employed for lowering the freezing point of the cooling medium ordinarily have a specific gravity difierent from that of water, the

freezing point of the mixture may be sub-.

stantially ascertained when the density of the coolant within the radiator is known.

Due to evaporation as well as other causes,.

some of the liquid that is mixed with the water within the cooling system is lost and it must be replaced from time to time, if the low freezing point ofthe cooling mixture is to be retained. Due to losses of this character, it is difficult to determine the exact pro- 0 portions of the anti-freeze liquid and water in the cooling system. Accordingly upon the one hand there is a possibility that so much of the low freezing point liquid will have been lost from the system that freezing may 5 occur with resultant breakage of expensive parts, while on the other hand there is a possibility that much more of the low freezing point liquid, which is comparatively expen- F sive, may be used than is necessary to avoid.

such a contingency.

Since the densities of the anti-freeze liquids ordinarily mixed with the cooling water differ appreciably from that of the water, the freezing point of any mixture within the system can be determined if the specific gravity of the added liquid is known. Accordingly, the apparatus provided by the present invention is particularly advantageous in permitting the ready and instant indication of the freezing point of a mixture within the radiator, a factor which it otherwise would be difiicult to determine.

In order to permit the reaaly determination of the specific gravity of liquid within a liquid containing system such as the cooling system of a water cooled motor, I preferably. provide two pressure responsive factors con- 11 cted to the cooling system at different levels 'se-that a column of liquid of predetermined height will normally be maintained between these levels. Preferably one factor which is responsive to the weight of the liquid head is connectedsubstantially tothe bottom of the cooling system while the other factor may be connected to the system at a distance somewhat below the top of the same so that an ordinary variation in the amount of liquid contained within the radiator will not affect the accuracy of the indication provided by these factors. Furthermore, the arrange ment of the upper pressure responsive factor in this manner also permits the indication of a dangerous reduction of the total amount of liquid contained within the system.

In order to permit an;indicator to be conveniently actuated in response to the condition of these two factors and to permit this indicator to be located at a convenient point as, for example, upon the instrumentboard of a conventional motor vehicle, each of the factors is preferably connectedto a gas containing pipe of restricted diameter. Each of these pipes in turn is connected-tomeans responsive to variation in gaseous pressure such as, for example, an e'xpansible capsule, or Bourdon tube. These members which are responsive to gaseous pressure are in turn connected through suitable gearing. and/or linkage to a pair of relatively movable indicating elements. One of these elements, such as a rotatable dial, may be connected-to the gas duct that is connected to the upper pressure responsive factor, while the other indicating element, which may be a pointer, may be assoeiated with the duct connecting to the lower pressure responsive factor. The relative position of these two indicating elements accordingly will vary in response to the differences in density of the liquid column between the two pressure responsive factors, and, since the weight of this column will vary in accordance with the amount of anti-freeze liquid mixed with water in thecooling systom, the relative position of .the indicating elements continuously-affords an indication of the freezing point of the anti-freeae solution employed. Furthermore, the position of the indicating element that is connected to the upper pressure responsive factor will de pend upon the amount of liquid above the latter; accordingly the position of this element in relation to a fixed point upon the gauge will afford a warning should the level of the cooling medium become dangerously low.

In the accompanying drawing which illustrates one concrete exemplification of the invention,

Fig. 1 is a somewhat diagrammatic s de elevational view of a motor and the cool ng system associated therewith, showing my improved indicating apparatusapplied thereto;

Fig. 2 is an elevational view of the indieating gauge; D

Fig. 3 is a central sectional view through thesame;

Fig. 4 is a section on the line 4-4 of Fig. 3;

Fig. 5 is a sectional detail of a typical pressure responsive factor; and

Fig. 6 is a sectional detail.

In the accompanying drawing, the numera1 1 designates a conventional internahcombustion engine for a motor vehicle which is provided with a cooling jacket 2 that is connected by a duct 3 to the upper portion of a radiator 4. The lower end of the radiator may be provided with an outlet duct 6 that s connected to a circulating pump 7 which in turn is connected to the lower portion of the cooling jacket by a duct 8. Ordinarily when the motor is running the pump is effective in aiding the thermo-siphonic circulation of the coolant from the lower portion of the rad ator to the jacket 2 and thence through pipe 3 to the upper portion of the radiator. Numeral 10 indicates the conventional cooling fan which is ordinarily employed in conjunction with a radiator of this character.

In accordance with the present invention, a pressure responsive factor 12 is preferably connected to the pipe 6 substantially at the lower part of the cooling system. As shown in Fig. 5, pipe 15 has a portion 17 of restricted diameter adjoining factor 12. The latter has a pair of oppositely dished portions 18 with peripheral flanges 19 clamping an edge of a flexible metal diaphragm 20 therebetween. Preferably this diaphragm may be provided with concentric undulations to afford greater flexibility. It is evident that an increase in the pressure within pipe 15 causes the central portion of the diaphragm. to be fiexed away from the outlet of the pipe. This will result in thecompression of gas contained in the member 12 at the other side of the diaplragm. This portion of th pressure responsivefactoris connected through a duct 23 of restieted internal diameter to an element 59 which is responsive to variation in ,gas pressure and which may be located within the gauge 30 upon the instrument board. The member 59- may conveniently be a Bourdon tube or expansible capsule or the like. The factor 12, pipe 23, and the Bourdon tube connected thereto form a hermetically sealed system containing a constant quantity of gas, such as air.

Adjoining the upper portion of the cooling system by located somewhat below the top of I the same, for example, one-fifth of the dis tance vertically between the top of the overflow pipe of the radiator and the pressure responsive factor 12, is a similar factor 42. The latter may have a liquid containing chamber 43 connected by a short pipe 45 to the pipe 3 and may have another connection 46 with the pipe 8 between the pump and the cooling jacket. Preferably pipe 46 has a restricted portion 48 (Fig. 6) to impede the flow of fluid through the chamber 43. If desired, pipe 46 may be provided'with a plurality of coolin fins 49 to lower the temperature of the liquid passing through chamber 43. Factor 42 may be provided with a flexible diaphragm 20 similar to that previously described in conjune tion with factor 12, and it may have a connection to a gas containing duct 53 of restricted internal diameter which in general corresponds to the pipe 23 so that the variation in the pressure imposed upon the diaphragm in factor 42' will result in a change in the pressure within pipe 53. The latter is connected to a suitable element that has a portion movable in response to changes in gaseous pressure such, for example, as a second Bourdon tube 29.

Preferably the tube 59 may be connected through suitable mechanism such as is shown in Fig. 4 to, an indicating element such as a pointer 60. For this purpose, for example, the .movable end of the tube may be pivotally connected to a link 57 which is articulated to the outer end of a crank member 58 extending from a toothed sector 64 that is mounted on a fixed pivot 63. The sector preferably is in meshed engagement with a pinion 65 fixed upon a rotatable shaft 66 which carries the pointer 60.

The other Bourdontube may be connected by similar mechanism to a rotatble sleeve 68 which is mounted upon the shaft 66 and to which the rotatable dial 70 is secured. It is thus evident that the pointer 60 will have its.

response to the conditions and amount of the liquid above the factor 42 will be movable over a range to indicate the variation in the liquid level from the top of the radiator to the level of factor 42. On the other hand the pointer will preferably be movable in response tovariation in the liquid level (as'-,

suming a liquid of the density of water to be employed) varying from a distance somewhat below the factor 42 to the top of the radiator. Thus, for example. the factor 42 may be disposed six inches below the top of the radiator and the dial 70 may have a range of movement of substantially 180 corresponding to the variation in the liquid level throughout this distance. cooling system to have a specific gravity of one, when the liquid level is substantially even with the member 42, the dial 60 may be dis posed at one end of its path, while, when the radiator is filled, the dial will be disposed adjoining the other end of its path or180 from the first position. The pointer also preferably moves 180 for a similar change in the level of the liquid under similar conditions,

but it also has an additional range of movement so that the liquid may fall somewhat below the member 42 and the pointer still move in response tothis change in the liquid level. Thus, for example, the dial may have a total range of movement through 270 and may be responsive to a pressure variation afforded by nine inches of water. While, for purposes of convenience and clarity of illustration, I have indicated that the dial and pointer movements end at a point correspond, ing to the filling of the system with water, it is preferable to permit some additional movement of these indicating. elements to permit the same to be movable in response to added pressure such as that resulting from the generation of steam or the use of a liquid heavier than water. I 1

Since both of the indicating elements have the same angular movement for the same change in liquid level. their relative positions will remain the same as long as the liquid level remains above the factor 42 and the density of the liquid does not change. When however, the specific gravity of the liquid column between the two factors is changed the relative position of the elements changes in a corresponding manner. Thus, assuming that a lighter liquid is mixed with the water in the system, the factor 42 which, for convenience of illustration has been assumed to be sub- Assuming the liquid within the jected to a liquid column or head of six inches,

will cause movement of the corresponding dial 70 similarto that which could occur if the 1 this factor is movable in response to the densityof the liquid column below. the factor 42, pointer 60 will have a greater angular movement than the dial 7 0, whereby the resultant relative movement permits an indication of the'density of the contained liquid. If any height of the liquid column had been decreased. Not only will a, lmilar change be communicated to the lower factor 12 but since anti-freeze liquid of known density is em ployed; for example,- if we assume alcohol is mixed with the cooling water, the dial can be provided with suitable indicia, which is arranged as a result of calibration to indicate by the relative position of the pointer 60 and the dial, the freezing point of a mixture of any proportions of these two liquids which may be contained within the cooling system. Thus referring to Fig. 2, if the system merely contained water the pointer 60 would register with the portion of the dial designated 32 and corresponding to the freezing point of water.

In the relative position of the indicator and dial shown, however, the pointer registers substantially with the mark designated 5 in dicating that the mixture now in the system has a freezing point of 5 F.

Not only is the gauge thus effective in showing the freezing point of the mixture contained in the system but it also may be employed to indicate when the amount of liquid within the radiator becomes dangerously low. For this purpose, a plurality of fixed graduations may bedisposed upon the gauge 30, as for example upon the glass 81 covering the pointer and dial. At one end of the scale provided by these graduations the word'full may be etched or otherwise imprinted and at the oposite end of the scale the word danger or any suitable designation mav be provided. A suitable arcuate mark 85 may be disposed upon the dial adj oiningthegraduationmarked 32, thismark being in the vicinity of the, graduation marked 'full when the radiatorissubstantially full. When this arc upon the d1al moves into the vicinity of the mark designated danger, the cooling system does not contain liquid subntantially above the level of the factor 42.

The arcuate mark has an extent correspondlng to the variation in angular positioning of the dial when different proportions tively low, even when the motor is warm;

accordingly there will not be a wide varia-' tion in the density of the liquid between the no I sive element and factor, whereby the relative the coolingmedium in the main circuit.

Furthermore the restriction in the diameter T of the liquid passages aids in preventing radical chan es in the temperature of the liquid passing tgrough the same, and is also helpful in dampening the effect of the pump upon the gauge. In this connectionit is to be noted that the indicator automatically and continuall will afford an accurate indication of I liquid conditions within the cooling system when the pump is not running and that depending more or less upon-the particular design" of the cooling system, this indicating means may still be substantially accurate when the pump is functioning.

I claim:

1. Apparatus of the class described comprising a pair of relatively movable indicating elements, a liquid container, a factor responsive to liquid head connected with the lower part of the container; a duct providing a liquid column and having both ends connected to the container, coolin means associated with the duct, a second actor responsive to liquid head and connected to the duct above the first factor, gascontaining ducts connected respectively to each of said factors, control means responsive to the respective gas pressures in said ducts, connections between said indicators and the control means, the indicators being movable in response to the control means to show the density of the liquid between said factors.

2. In combination a cooling jacket, a radiator, a duct connecting the upper part of the jacket to the upper part of the radiator, a

' pump, a duct connecting the lower part of the radiator and the pump, a factor responsive to liquid head connected to said lastnamed duct, a duct connecting the pump and the lower part of the jacket, a pipe with cooling means connecting the first-named duct and the duct between the pump and jacket, a factor responsive to liquid head connected to said pipe adjoining its juncture with the firstnamed duct, a pair of gas pressure responsive elements, a gas-containing duct between one of said factors and one of the gas pressure responsive elements, a gas-containing duct between the other of said factors and the other of said factors and the other of said elements, a pair of relatively movable indicating parts, means respectively connecting each of said parts to one of the gas pressureresponsive elements so that each of said parts is movable in response to a change in condidition of the corresponding pressure responposition of the indicating parts indicates the density of a liquid column between the aforesaid factors.

3. In combination a cooling jacket, a radiator, a duct connecting the upper part of the jacket to the upper part of the radiator, a pump, a duct connecting the lower part of the radiator and the pump, a factor responsiveto liquid head connected to said lastnamed duct, a; duct connecting the pump and the lower part of the jacket, apipe with cooling means connecting the first-named duct and the duct between the pump and jacket,

an upper factor responsive to liquid head connected to said pipe adjoining its juncture with the first-named duct, a pair of gas pressure responsive elements, a gas-containing duct between one of said factors and one of the gas pressure responsive elements, a gascontainingduct between the other of said factors and the other of said elements, a pair of relatively movable indicating parts, means operatively effective to cause one of said parts to be movable in response to each of the gas pressureaesponsive elements and a gauge element bearing fixed indicia disposed adjoining the part that is responsive to thehead above the upper factor, whereby the position of one of the indicating parts isresponsive to the pressure .above said first named factor and whereby the position of the other indicatlng part is responsive to the pressure above said second named factor, so that the relative position of the indicating parts automatically indicates the density of the liquid column between the aforesaid connections, and whereby the position of the indicator responsive to pressure above the upper factor indicates by its relation with the fixed indicia the approximate liquid level above said upper factor.

4. In combination a coolant circuit including a cooling acket, a pump, a radiator and connecting ducts, a factor responsive to liquid head connected to the lower part of the circuit, a second factor responsive to liquid head connected to the circuit substantially above the first factor but somewhat below the upper part of the circuit, a gauge comprising a pair of relatively moving parts, and a fixed part with indicia thereon, actuating means between one of said moving parts and one of the factors operable to cause that part to move in response to changes in liquid.

head above that factor, similar actuating means between the other moving part and other factor, the position of one of said moving parts being changeable in response to a change in liquid head in the part of the circuit above the upper factor, the other of said moving parts having its position changeable in response to variations in the liquid head above the other factor, so that the relative position of the parts thus automatically indicates'the specific gravity of the liquid in the circuit, while the relative position of said indicia and said moving part whose position changes in response to pressure upon the up- .per factor, indicates the liquid level above the upper factor.

5. In combination with a cooling jacket,

a radiator, a pump, a duct connecting the radiator and pump, a duct connecting the radiator and jacket, a duct connecting the pump and jacket, the ducts which are connected to the radiator being connected to the lower part and the upper part of the radiator respectively, the ducts connected to the jacket being connected to the upper and lower part I of the jacket respectively, a factor responsive to liquid head connected to the duct that is connected to the. lower part of the radiator, a pressure stabilizing pipe of restricted diameter connecting the upper of said ducts with the duct that connects the jacket and pump, a second factor responsive to liquid head connected to the upper end of said pipe, a pair of relatively movable indicating parts, means connecting one of said parts to one 2 of said factors to cause that part to move in response to liquid head above that factor. and similar meansconnecting the other'part' and factor, whereby the relative positioning .of the indicating parts indicates the density of the liquid between the aforesaid factors.

Signed by me at Boston, Massachusetts this 8th day of June 1929.

LEE PERKINS. 

